‘Phlogiston’ is an interesting, if obsolete, word. Of Greek origin, it referred to the ‘fire-making’ quality thought to be present in, among other things, the ashes gathered by London dustmen. In the mid-18th century these ashes were mixed with earth and even ‘excrements taken out of the necessary houses’ to create the vast numbers of bricks needed for the explosion of house-building taking place at the time in London and elsewhere.